It’s a maxim repeated all over the internet, and it keeps popping up in debates between Christians and atheists. But what exactly is the phrase telling us? Do extraordinary claims really need extraordinary evidence? And what exactly qualifies as “extraordinary” evidence anyway?

Is it true?

Do extraordinary claims really need extraordinary evidence? Well, intuitively, it seems the answer yes. But is it really true?

Suppose I were to claim that I were not a human, and instead am a giant pink salamander. What kind of evidence would be required in order to back this claim? Well I could obviously submit pictures of myself typing these blog posts as evidence. I could submit videos. I could allow people to come observe me. None of these would really be “extraordinary” types of evidence. Merely observing something is nothing extraordinary. But these could certainly serve as proof for my claim. People would be justified in believing me upon observation–it’s possible that they could be within their epistemic rights simply by seeing pictures of me typing (though with Photoshop and the like, it is more difficult to justify that epistemically).

So despite our intuitions, it seems there must be some kind of argument to establish the truth of the phrase. It seems, upon further thought, that the phrase is false. Ordinary evidence (x observes y to be the case, therefore, x believes y is true) will do even for extraordinary claims. Examples of this nature could be multiplied. So it seems the phrase, on this interpretation, is simply false.

What qualifies as an ‘extraordinary’ claim?

Another problem with the statement “Extraordinary claims need extraordinary evidence” is that those who make the claim never explain what exactly it is that qualifies as an “extraordinary claim.” I mean surely, we could reduce almost any claim to something extraordinary, if we worked hard enough. I claim to be human; that entails a huge amount of ontology such as the existence of a planet which is capable of supporting life, the existence of life on said planet, the higher order of life such that intelligent life could exist, intelligent life which created machines capable of typing out thoughts, etc, etc. Any claim could be said to be “extraordinary”. The attack on “extraordinary claims” fails, in part, because it does not define what qualifies as “extraordinary”. I suspect this is another case of proving too much or not enough: either all claims are extraordinary and not to be believed until we have overwhelming evidence, or claims need just enough evidence to be justified in believing them.

Without a clear explanation of what qualifies as an “extraordinary claim” (and I think there can be none offered without begging the question), there is no reason to accept the statement as true to begin with. But this leads us to the next level:

What is ‘extraordinary evidence’?

What exactly is “extraordinary evidence” anyway? The phrase is thrown around as though it has meaning, and for someone studying philosophy with a heavy analytic bent, this is maddening. What is meant by “extraordinary”!? I think it could give us one of two options: either a) a large amount of evidence; or b) extremely powerful evidence. But even these definitions are ambiguous: what constitutes a “large amount” of evidence or “extremely powerful” evidence?

The phrase therefore seems to rely upon a certain ambiguity in order to maintain its power. There is no clear definition of what constitutes extraordinary evidence; and it seems likely that the phrase is merely used to try to increase the burden of evidence on the theist. Without a clear definition or any kind of argument to support the assertion, however, the theist is justified in rejecting it.

Is that the issue?

Perhaps I’ve missed what’s really the issue here. I suspect the reasoning is that the phrase is meant to refer either to:

1) Things which can’t be observed in the usual fashion

2) Things of great existential import

Consider 1) first. The reasoning here could be that something, like God, which can’t be observed simply by going somewhere and staring, would need extraordinary evidence in order to justify belief in said being. The problem here is that the definition of extraordinary is being used differently than (I think) the phrase is intended. For here, extraordinary would have to mean simply”other” than the ordinary. There would have to be some kind of evidence for a thing’s existence such that it would act as a substitute for “seeing” the thing. But that doesn’t mean we need “more” or “greater” evidence for something described by 1) than we would for something which is a standard, everyday kind of thing. All it means is that we’d have to have a different kind of evidence.

What kind of evidence, specifically? Well it seems as though logical evidence or philosophical argument could serve as a valid substitute for empirical evidence. So either of those could serve to justify someone in her belief in a deity.

Consider 2)–that claims of great existential import need extraordinary evidence. William Lane Craig discussed this in his Reasonable Faith Podcast, “Doubting the Resurrection.” He asserted that if something is of existential importance, we don’t demand more evidence for it; if anything, we should be more open and eager to explore the viability of the claims. Craig proposed the following example: suppose you are diagnosed with a fatal disease and there was “some experimental evidence that a vaccine… might cure you, wouldn’t you be desperate to [try the medicine and] find out if that might save your life… rather than saying, ‘Well, this is such a life-changing situation that I’m going to be as skeptical as I can, and only take this medicine as a last resort when it’s been demonstrated absolutely that” it will cure the disease.

The key point is that claims of extraordinary existential significance require evidence, but they are of such import that it is almost absurd to be totally skeptical of these claims due to their total importance. As Craig points out, if God exists and sent His Son to save us through belief in Him, that is such an extraordinarily significant difference between the universe if that is true as opposed to if it is false that it is worth exploring. He points out that even if there’s only a 1/1,000,000 chance that it’s true, it is worth looking into.

The most obvious rebuttal to this kind of reasoning is a kind of argument from religious diversity: “All the world’s religions have existential significance, and it would be impossible to fully explore all of them in a lifetime”… therefore, what? Perhaps one could argue that because we can’t explore all the options, we shouldn’t bother with any–but that seems to be throwing out everything for no reason. A diversity of options does not entail the falsehood of all.

It may be best to instead look at world religions in light of the kinds of evidence which could be available, and take 1) above with 2) to yield an exploration of religions based upon the types of evidence available for them. For example, the Qur’an contradicts the Bible on the topic of whether Jesus was crucified. Yet we have irrefutable evidence that Jesus was indeed crucified from both Gospel accounts and extrabiblical, contemporary accounts. Therefore, one could see it fit to exclude Islam from the exploration and move on. Perhaps one finds the existential claims of Buddhism less compelling than that of Judaism–in such a case, she would be well within her epistemic rights to explore Judaism rather than Buddhism.

A complete answer to this objection would take us far afield, but for now I think that it may be best to note simply that the objection does not undermine the argument against 2) anyway. As noted, a mere diversity of positions does not entail they are all false. Similarly, our inability to explore all possible options does not mean we should explore none. Perhaps it means, instead, that we should get started.

——

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About J.W. Wartick

J.W. Wartick has an MA in Christian Apologetics from Biola University. His interests include theology, philosophy of religion--particularly the existence of God--astronomy, biology, archaeology, and sci-fi and fantasy novels.

Discussion

47 thoughts on ““Extraordinary claims need…” What, exactly?”

Hey jw this is a very interesting and relevant post. I can’t speak for every atheist, but when I speak about extraordinary claims, I refer to things which upend fundamental impressions of reality built upon a wealth of evidence (be it evidence derived from controlled experiments or just everyday experience). For example, the proposition that the passage of time varies with the speed of an object is an extraordinary claim, because every day we exist we see time passing at apparently the same rate for everyone, and this seems to have gone on for all of recorded history completely uninterrupted. Extraordinary evidence was provided: they moved two atomic clocks at vastly different speeds and were able to predict the differential that developed, making their data publicly available, and the results were duplicated by others on numerous occassions. Why is that extraordinary evidence? Because this new model reliably predicts and explains events that are not sensible or tractable in the prior model. It is also extraordinary because the prediction was made prior to the initial test.

There is another important aspect for evidence to qualify as ‘extraordinary,’: independent verification. If only a handful of people had tested the atomic clocks (and other experiements validating relativity), and for whatever reason left us no way to duplicate their results, I would not be persuaded that relativity is true. Independent verification it is the only way to control for eyewitness ‘noise,’ which is extremely pernicious.

Likewise, everyday we exist we see dead people staying dead, and we see the law of entropy and all other physical laws continuing on the way they’re supposed to, and we see frank miracles not happening. Reports that these principles get violated come in all the time, but on the occassions when they can be closely scruitinized in controlled settings they are always found to be in error. As such the claim that these principles get violated is extraordinary because
A) Physical laws don’t seem to get violated (in the same sense that time seems to move at a steady pace) and
B) Claims that physical law gets violated are common even when physical law has not in fact been violated.

This sort of rationale is the only reason why I don’t believe in UFO’s. There are millions of people reporting UFO sightings and abductions, and though most of them seem a little imbalanced they seem – on average – basically sane and sincere. The problem is that there are lots of reasons to suppose, on our current best understanding, that aliens who happen to look basically like us making it all the way over here to harvest our genes is a very unlikely scenario. As such, it needs better evidence. The reports are more easily explained by human error due to a variety of social pressures and psychological factors.

—Anticipated Objections:———————

Objection 1) You would be right to point out a certain ambiguity in the way I evaluate probabilities (who is to say social pressures and psychological factors are actually more likely than aliens with such advanced technology coming over to abduct us), but I don’t see a better alternative for any of us. If I could provide a deductive mathematical proof that would be great, but I don’t think anyone is demanding that. Instead we can loosely trace the likely implications of our current best ‘reality maps’ and make comparisons.

Objection 2) ‘but everything could be easily explained by human error. My conviction that I’m sitting at a computer could be human error.’ This is like the brain in the vat proposition: it is more likely that my brain randomly formed itself with the impression of an imagined world than that the world randomly formed itself with a brain that could comprehend it.

The first problem is that the brain in the vat assumes complexity only arises through pure randomness, but lets leave that aside.
1) If everything were sporadic illusion, random fluctuations in our heads with no real connection to an objective reality, then we would not expect to have this impression of a patterned coherent reality. We would expect subjective chaos.
2) This is not what happens. Rather things make sense, and we can predict events before they happen when we apprehend the important functional factors. Therefore, we can reasonably conclude that there is probably an acutal objective reality which we’re percieving.

Of course the data comes in with a lot of intermediary noise, and the whole point of science is to disentangle that noise from actual events. That’s why controlled experiements are so important, they provide the ability to reduce the amount of unnaccounted noise from observation.

Objection 3) Christianity attempts to control for eyewitness noise with the torture early christians endured as a result of their belief, but this seems like a poor control to me. Torture can expose outright lies (although I doubt it even does that very well), but it doesn’t expose other forms of error such as a bias for affirming group solidarity, frank delusions, political motivations, etc. Even if it did, independent verification is far better. Regardless of how early Christian’s motivations for belief may have actually been distributed, the point is we’re talking about complex and fallible human beings with their own motivations and personalities which we can never directly inspect in a completely alien culture where witchcraft was a going concern. Ultimately the point is that whatever duress they were put under they were still people, and people make these mistakes, especially people in religiously saturated communities. If we could control for this and independently verify the ressurection (for example, if prayer to Jesus reliably produced physically inexplicable events), we’d have something to go on. Unfortunately, God is not so helpful.

Objection 4) “what about philosophical arguments for a ‘broad theistic’ framework, disregarding God’s specific revelations to humans.” I personally don’t think any of these are very good (and so obviously not very extraordinary, though obviously we disagree on this), but I suppose if someone came up with a philosophical argument that was sufficiently airtight I’d be compelled to accept it. Part of the problem for me is that the philosophical arguments employ so much pure linguistic reasoning. The farther you reason without checking up with observation the more likely that subtle oversights slip into your logic. That’s not a refutation of anything, just a reservation.

JWW, you are my kind of atheist. I really enjoyed your thoughtful and thought-provoking reply to this very interesting blog post. Very relevant objections and very focused. (And I’m not just saying that to be nicey-nice. I mean it.)

I’ll go back to watching from the sidelines, but if your replies are always this focused and thoughtful, I look forward to reading more of them.

Thanks for your thoughtful and lengthy response. I’m not sure I can do it total justice.

I want to point out a few problems with the reasoning here.

1) it doesn’t seem as though you’ve established a difference between evidence for “extraordinary claims” and “ordinary claims”. Your paradigm example was that of UFO sightings. But what is it that makes the UFO sighting extraordinary? Consider your wording, “There are millions of people reporting UFO sightings and abductions, and though most of them seem a little imbalanced they seem – on average – basically sane and sincere. The problem is that there are lots of reasons to suppose, on our current best understanding, that aliens who happen to look basically like us making it all the way over here to harvest our genes is a very unlikely scenario.” This doesn’t go against the sighting of a UFO; it only challenges the interpretation. I think we would both be perfectly willing to grant that those who sight UFOs see something; we differ in how we interpret it. They argue it is due to aliens or somesuch; we believe it is due to either natural phenomena or airplanes or some other event caused by humans. So I don’t think the UFO example works because it is a challenge not so much against the claim “I spotted x” but against the interpretive content of the statement “x was y” (in this case, aliens). This leads to my next point:

2) I’m going to add this insightful problem my fiancée pointed out upon discussing this post, but it is only fair to point it out to you as well: those who make the claim never explain what exactly it is that qualifies as an “extraordinary claim.” I mean surely, we could reduce almost any claim to something extraordinary, if we worked hard enough. I claim to be human; that entails a huge amount of ontology such as the existence of a planet which is capable of supporting life, the existence of life on said planet, the higher order of life such that intelligent life could exist, intelligent life which created machines capable of typing out thoughts, etc, etc. Any claim could be said to be “extraordinary”. The attack on “extraordinary claims” fails, in part, because it does not define what qualifies as “extraordinary”. I suspect this is another case of proving too much or not enough: either all claims are extraordinary and not to be believed until we have overwhelming evidence, or claims need just enough evidence to be justified in believing them.

3) Your thinking is obviously based on prior probability (see your explanation of objection 4). You have assigned a low prior probability to non-theism and therefore hold that theism needs some indeterminate amount or quality of evidence in order to be accepted. But this is simply arguing by fiat; you haven’t established any reason to think theism has a low prior probability or that the arguments to the existence of God fail. I think we can both agree that this objection would take us very far afield, so it may be best to leave it aside for now.

Late to the party, but I’d like to’ ask why indeed does the example on special relativity you offered count as extraordinary evidence? It is a prediction of special relativity that in a specific set of conditions the laws of classical of physics — our common no-nonsense everyday physics — are overturned and some new phenomena emerge, but notice the antecedent: specific set of conditions. In other words, to actually see the difference between classical and relativistic physics you have to have uncommon physical conditions, and for that you have to have a necessarily more complicated experimental apparatus. But why does more complicated experimental apparatus count as “extraordinary evidence”? To my own eye, it is just ordinary evidence; it follows the standard protocols of physical experiments, standard rules of measuring and interpretation are applied, etc.

I do not wish to engage the second “independent verification” condition; I would just like to note that it raises many problems, e.g. in History. Historians for example, commonly deal with unreliable evidence, but they have learned how to extract an historically correct core from such evidence.

My impression is that people that bandy around this “extraordinary claims need extraordinary evidence” slogan, are people of a thouroughly naturalistic bent, and will only admit the sort of evidence that counts in the physical sciences. My response would be, taking a simple example from mathematics, do you accept Euclid’s theorem that the set of prime numbers is not finite? Certainly there is no experiment we can concoct to justify this claim; things like prime number or non-finite sets are not physical things. And yet there is a very simple constructive proof of this fact using only ordinary principles of reasoning. What I am trying to get at is that maybe what counts as evidence should be widened a little? This is precisely one of the points of post, that deductive or philosophical arguments can be of use for when empirical evidence, of its own nature, is no longer available.

Sorry to post on this so late after the last posting. It started to seem relevant to me again after some of the other discussions we’ve had.

to 1) As you say, I’m not disputing that UFO conspiracy theorists think they have seen things. I’m also not disputing that the early christians may have thought that they witnessed the resurrection of christ (perhaps seeing an open grave that they misinterpreted, perhaps seeing someone who looked like christ, perhaps seeing christ again before he really died, perhaps seeing this in a dream, perhaps speaking metaphorically, or perhaps a mashup of all of these).

to 2) This may be a confusion as to how atheists use the word “extraordinary.” Try substituting “far fetched claims require more substantial evidence” and maybe you will get the better gist of what we are saying. This is the whole point of brining up the UFO sightings. Just what process is it that leads you to view the claims of UFO conspiracy theorists as erroneous?

to 3) As you say its another conversation (I think our discussion of Kalam Cosmological argument addresses it a bit more), but in this post I was speaking more about miracle reports than theism, which are linked but not identical.

lol. It would really help if you could explain how you come to disbelieve a proposition (I find the UFO example instructive) so that I can see if we’re doing it the same way. I’ve tried to explain the way I do it, but I’m still not entirely sure what you think the alternatives are.

This entire argument is a case of special pleading, and a dishonest one at that. You live every day by the principle that extraordinary claims require extraordinary evidence; it is only in this particular area, when it represents a threat to your preferred view of the world, that you argue it does not apply.

Consider the following three claims:

1. A friend claims that he spotted a deer in the wild on the way home from work

2. A friend claims that he spotted an elephant in the wild on the way home from work

3. A friend claims that he spotted a unicorn on the way home from work

Are these claims equally believable? What sort of evidence would you require before believing each of these claims? If the evidence necessary differs between the claims, why is that?

A rational person would require varying degrees of evidence before accepting each of these claims:

The first, one would generally believe without question; Seeing a deer is not at all unusual (depending on what part of the world you live in. I’m in Tennessee so I’ll assume that setting for all three).

The second would require some sort of proof to demontrate why an elephant would be running loose in TN. Perhaps a news segment on an elephant having escaped the zoo, and some corroborating witnesses.

The third should not be accepted based on anything less than actually seeing a unicorn oneself. It is more likely that video evidence, witness corroboration, or any other second-hand account is doctored, mistaken, or otherwise false than that a mythical creature exists and was seen physically walking the earth.

When you say that “Merely observing something is nothing extraordinary” you are mistaking evidence with the means of acquiring it. Observation is not an extraordinary means of acquiring evidence, but a giant pink salamander is absolutely an extraordinary piece of evidence. The evidence is the salamander itself, not the observation of it. Nobody means to argue that evidence has to be acquired in an extraordinary way, but if an extraordinary claim is to be believed, the evidence provided for it must certainly be extraordinary–however it is presented.

If you were honest with yourself, you would see that most of what you do assumes the truth of this very principle you have attempted to refute. Otherwise you would believe everything you were told just as easily as you believe that your buddy saw a deer.

It is unfortunate that you and most of the world are so irrationally committed to a worldview for which there is absolutely no evidence that you feel obligated to denigrate the role that evidence plays in the rest of your own life.

Note that the post focused first upon one’s individual justification. In the first argument I clearly stated, “Ordinary evidence (x observes y to be the case, therefore, x believes y is true) will do even for extraordinary claims.”

In regards to the pink salamander you wrote, “The evidence is the salamander itself, not the observation of it.”

What evidence would the salamander provide, if not observational evidence?

Further, I already answered the second thrust of your comment, which is that those who use this phrase provide no clear criteria for determining what “extraordinary” means. You’ve provided only the weakest attempt at doing so by saying “A rational person would require varying degrees of evidence before accepting each of these claims”

But why, and by what principles? What constitutes “extraordinary” and what kind of evidence does it require.

To sum up, rather than actually rebutting any claim I made in this post, you’ve just reiterated the statement. Finally, if you want to talk about “special pleading” how about your own words, “If you were honest with yourself…”

I didn’t realize you were capable of reading minds. Is that an extraordinary claim?

You have not argued against the maxim, “extraordinary claims require extraordinary evidence,” you have invented and debunked your own maxim: “extraordinary claims require extraordinary KINDS of evidence.” These statements are entirely different, and you have yet to address the first.

You are trying to define “extraordinary evidence” out of existence by equating it with the method of aqcuisition. If nothing observed counts as extraordinary evidence because the method of acquisition (observation) is not itself extraordinary, then you’re certainly correct in saying that no claim requires extraordinary evidence. By this definition, I have no idea what could possibly qualify as extraordinary evidence.

Your whining about the definition of “extraordinary” sounds like a politician caught in a lie trying desperately to save face. Will you be asking me to define “is” as well? I hope you can forgive me for considering it futile to argue the definition of “extraordinary” with someone who won’t admit that a giant blogging salamander fits the bill.

I would love for you to answer my previous questions (which you ignored) regarding the three scenarios I posed: are they equally believable? What sort of evidence would you require before believing each of these claims? If the evidence necessary differs between the claims, why is that?

I didn’t directly address much of your comment because it’s largely full of red herrings. The post on which you’re commenting specifically argues for the justification of belief. Thus, I’m arguing on an epistemic level for one’s own beliefs. If someone sees a unicorn, they’re justified in believing they saw one. This is an epistemic question and you’re trying to push it beyond that.

You wrote, “I hope you can forgive me for considering it futile to argue the definition of ‘extraordinary’ with someone who won’t admit that a giant blogging salamander fits the bill.”

Again, but this is the point of the post itself. I am asking for those who want to defend the claim to provide a definition of terms. The perpetuation of this claim is due, I think, largely to the fact that people don’t have any idea what they actually mean when they say it. For example, you’ve come along and simply offered examples of things you think show a distinction. But where is the distinction? What qualities make the distinction? How do we know when something has crossed the line from “ordinary” to “extraordinary?”

I recommend taking a step back on the sarcasm as well. This is an area for serious debate, not snide remarks.

“I didn’t realize you were capable of reading minds. Is that an extraordinary claim?”

Hello pot, I’m kettle. Let’s not pretend either of us has a monopoly on sarcasm, though criticizing the tone of argumentation is understandably easier than criticizing the argument itself. There’s nothing wrong with a little sarcasm, which makes debating more fun, as long as it is restricted to the argument and not the person making it.

As to your charge of red herrings, it would be much more constructive if you were at least a little specific. If you need an example of how to specifically and effectively point out a red herring argument, see my last comment.

I fail to see how my questions, which you have now twice refused to answer, do not apply to the current discussion. As I see it, they deal precisely with what we are discussing. If you are so afraid to answer them, perhaps you could explain to me why that is, or why they are irrelevant?

You seem to be under the impression that “extraordinary” is a line in the sand which one can cross at a specified point, and which needs to be precisely defined. This is not so. My purpose earlier in providing three scenarios as opposed to two was to demonstrate that this is not a yes or no proposition, but a continuum; the second claim was more extraordinary than the first, but less than the third. And dozens more intermediate levels could be added in between any of them.

Perhaps you could accept a definition along these lines: a claim becomes more extraordinary as it becomes less in line with what we would expect given the sum of our experiences. If you don’t like this, feel free to submit your own.

You wrote, “Perhaps you could accept a definition along these lines: a claim becomes more extraordinary as it becomes less in line with what we would expect given the sum of our experiences. If you don’t like this, feel free to submit your own.”

Why should I accept this definition? Also, why should I be expected to submit my own definition to support this axiom when I deny the axiom itself?

Not sure what leads you to that conclusion. I simply asked you to provide a reason to accept your definition. It doesn’t seem to have any clear way to apply it to philosophical cases. As a dictionary definition it might do alright, but philosophically it would need to be extensively filled out to even begin to be useful. For example, what does “sum of our experiences” mean? Is it our own, personal experiences, or public experience? Aren’t all experiences personal? Must they all be public?

And what proportion does something get more extraordinary. Is it a 1:1 ratio, or as things get more extraordinary, does it increase 2:1; 3:1?

The definition doesn’t seem to do any more than the statement itself: sounds impressive, until examined.

This is exactly why it is a waste of time to debate definitions with someone who is trying to weasel out of something; no definition will ever be satisfactory.

As you have refused to do so, allow me to point out why you have still refused to answer the questions posed in my first comment:

If you deny that belief in these three claims require varying degrees of evidence, and affirm that you would just as likely believe one as another, you are forced to confront head-on the foolishness of what you are claiming, and you lose your already shaky semblance of rationality.

If you admit that you would indeed require varying degrees of evidence, then you have admitted defeat. The more extraordinary the claim (or unlikely, incredible, unusual—surely one of these words is intelligible to you), the more evidence is required to believe it.

Again, you base most of your decisions on the truth of this axiom. It is not controversial, and there isn’t the slightest debate about its real-world applicability. You are happy to apply it when you see a pop-up ad informing you that you are the 1,000,000th visitor and winner of a prize, or when you receive an e-mail from Nigerian royalty who promise you a large sum of money for a small investment up front.

It is only when this same axiom which you rely on in every other area of life demonstrates the absurdity of certain irrational claims that you desperately try to concoct ways in which to argue against it—all the while continuing to assume its truth in all areas save for this one.

Again, the reason I don’t feel the need to answer your questions is because they are inapplicable. The question isn’t whether others are justified in believing the same thing as I do; the question is justification of one’s own belief, as I clearly stated in the post. Either you have refused to read the post and just argued whatever you desired, or you’re purposely misrepresenting my argument.

I have no idea why you consider these inapplicable, if indeed you really do and it isn’t just a flimsy excuse for avoiding the questions. I am asking whether YOU would be justified in believing a friend who claims any of these three things, whether YOU would need varying degrees of evidence for believing each one. This question has nothing to do with what OTHER people believe, and I don’t see how you could have thought it did.

If they really are inapplicable, you certainly haven’t explained why, and I am pretty sure that you can’t. Which would explain why you haven’t tried to.

I point out specifically in the post that I am arguing for the justification of one’s own belief. For example, “People would be justified in believing me upon observation–it’s possible that they could be within their epistemic rights simply by seeing pictures of me typing (though with Photoshop and the like, it is more difficult to justify that epistemically).”

Rabbit trails just aren’t any fun when they make you look like a fool, huh?

Not that these come anywhere close to being rabbit trails. They address the issue at hand as directly as any illustration could, and you have yet again failed to give any evidence to the contrary. There’s no need in my repeating myself; until you are willing to answer these questions or provide some justifiable reason not to, this discussion is over.

I agree the discussion is over. I repeatedly pointed out that you’re arguing against something I did not assert. I went so far as to point you towards quotations. You continued to ignore this. Oh well.

JWW, you’re just watering down the essence of the word extraordinary to make it far less than what it is. Yes the varying levels of “extraordinary” are subjective, but never could it stoop so low as to go down to “ordinary.”

Many become ex-christians because they didn’t even see RUDIMENTARY evidence of God’s claims in their life after dedicated decades of servitude, sacrifice, passion, and zeal. Not a single answered prayer of miraculous intervention, fulfilled promises, no supernatural “presence”, etc. (other than coincidence and placebo power of suggestion)

So since we didn’t get even rudimentary/basic evidence of God, and feeling duped, lied to, and cheated… we upgraded that to needing “extraordinary” evidence. Apologists want us to downgrade our demands for evidence, like by watering down the word “extraordinary”…whereas atheists are asking for something that goes beyond an ancient mythological scrapbook compiled on hearsay by superstitious zealots.

We would never sentence a murder suspect to the death penalty based on hearsay or mere testimony. There must be preponderance of the evidence beyond a reasonable doubt. There must be motive, 3rd party corroboration, lack of alibis, surveillance video, DNA testing, forensic science, etc. to really determine whose claims are correct.

So that is my definition of “extraordinary evidence” that is required for someone to believe the extraordinary claims that God will send you to hell if you do not believe in this man-made scrapbook of hearsay. If you think you have the justification to say that we’re going to hell for not believing, then you better have “death row evidence” to convince me that your God is the one true God that I need to alter my life for.

I agree that it depends on the prior probability. But I think it would be a common understanding that an ‘extraordinary claim’ would be a low prior probability, which would mean that the consequent probability would have to be high in order for the conclusion to hold.

Do you mean that the people discussing the claim do not agree on what that prior probability is? Or the consequent probability in relation to the prior probability?

They are no less objective than any other form of reasoning, though. In fact, wouldn’t this objection condemn all forms of reasoning, not just Bayes’ Theorem?

Something Richard Carrier wrote about this objection was that if you have access to evidence that others do not (such as previous experiences that others do not have), then you can still warrant your own belief, but it needs to be acknowledged that other people are doing the same thing, so they might disagree. He gives an example of a person abducted by aliens:

For example, you may be certain you visited an alien spaceship last night, but everyone else only has a vast body of background knowledge establishing that most (if not all) such experiences are hallucinatory or fabricated. You have to respect the fact that they are fully warranted in rejecting your testimony–until such time as you can prove your experience was genuine in a way that so many others were not, with evidence that others can observe.

But even if you have a high prior probability for your claim (h), you would have a low prior probability for the competing claim (~h), and it would still take extraordinary evidence to make your conclusion change. And because every claim has a nonzero probability of being true or false (unless its being true or false is logically impossible), this would always hold.

So while two people may not agree about what the prior probability is, the claim ‘extraordinary claims require extraordinary evidence’ would still hold, whether it is to prove or disprove a hypothesis.

I think there is some confusion here. First, you wrote “every claim has a nonzero probability of being true or false (unless its being true or false is logically impossible), this would always hold.” This is false. Things are either true or false (bivalence). I think you are confusing our ability to know something with the truth value of something.

Second, the way you have defined the phrase “extraordinary claims…” makes it essentially meaningless. Subjectively, all claims contrary to what one believes would therefore be judged extraordinary. I just don’t see how one can hold such a position without falling into radical subjectivism.

Yes, I am speaking about an epistemic probability, which is what Bayes’ Theorem shows. I agree that things are either true or false, but the claim has a nonzero probability of being true or false:

By “possible” here I mean a claim that is possible in any sense at all (as opposed to a claim that is logically impossible), and by “probability” here I mean “epistemic probability,” which is the probability that we are correct when affirming a claim is true.
-Richard Carrier

I don’t think this is a very controversial statement, because unless the truth (or negation) is logically impossible, we could always be wrong.

Background knowledge (in Bayes’ Theorem it is signified by P(h|b) ) is always dependent on everything that you know. If you don’t know it, how could you possibly take it into account? If P(h|b) is very low, then it would be an ‘extraordinary claim.’ And if there is extraordinary evidence (a high P(e|h.b) in Bayes’ Theorem), then you will reach a result that warrants belief. Assuming you accept the validity of Bayes’ Theorem (which I would think you would, given that it has been formally proven), this is demonstrable.

Now, as to what ‘extraordinary claims’ is defined as (a low prior probability), I’m not quite sure how this would lead to ‘radical subjectivism’ any more than any other form of reasoning. All Bayes’ Theorem does is translate words (such as ‘not likely’ or ‘very probable’) into percentages. Wouldn’t this, in addition to reviewing the formula with others, actually make the answer less subjective?

Well again, I think you are conflating the truth of a claim as opposed to belief in a claim. The distinction needs to be very explicit. Bayesian epistemology deals with probability, but it does not say that something is “probably true” only that we should believe that something is probably true (or not).

The usage of Bayes’ theorem in epistemology is not uncontroversial either, and I think the language you’re using suggests it is not. While I tend to lean towards Bayesian reasoning, I do not think that it is unequivocally the way that we gain epistemic justification. And I’m not being very radical here–there is significant debate that continues over various theories of epistemology, and Bayesian epistemology is but one among many branches thereof.

So I can accept the validity of Bayes’ theorem, but I am hesitant to apply it as ardently as you are doing.

Finally, it seems you are misunderstanding my point. I know about Bayes theorem, but I appreciate your reintroduction to it (I tend to specialize more in deductive reasoning and modal logic than inductive logic). Perhaps I have not been clear. What I’m saying is that if you believe that God’s existence is extremely improbable given your background knowledge, then it does seem more likely that you will say that it needs “extraordinary evidence.” But the point I made in this post is that there are all kinds of claims that can be made which may seem extraordinary, but do not require any kind of “extraordinary” evidence. Cf. the example of simply seeing something. It is not “extraordinary evidence” to perceive something; yet it would certainly justify belief that an object one perceives exists, whether or not one thought that such things existed. So I think you’re coming at me from the wrong angle here. My points in this post are a direct attack on the idea of “extraordinary evidence”; that is, I’m not at all convinced there is such a thing.

Thus, I think that you’re coming at me from an angle that is simply off course. In this post I specifically point out that I’m unconvinced there is any such thing as extraordinary evidence, or that one requires it to believe something (again, simply seeing something or experiencing it seems to be sufficient). Further, I attacked the concept of an “extraordinary claim.” Now what you’ve proposed is that the way to determine an “extraordinary claim” is to look at background knowledge. But if that’s how you want to define it, then any claim which seems out of the ordinary to an individual can in some way be extraordinary. And that’s why I say it implies radical subjectivism.

I think you are conflating the truth of a claim as opposed to belief in a claim. The distinction needs to be very explicit. Bayesian epistemology deals with probability, but it does not say that something is “probably true” only that we should believe that something is probably true (or not).

I’m not sure why you think I’m mistaking the two. I thought I was clear that I was talking about epistemic probability, so I would appreciate it if you point out where I seem not to be.

The usage of Bayes’ theorem in epistemology is not uncontroversial either, and I think the language you’re using suggests it is not. While I tend to lean towards Bayesian reasoning, I do not think that it is unequivocally the way that we gain epistemic justification. And I’m not being very radical here–there is significant debate that continues over various theories of epistemology, and Bayesian epistemology is but one among many branches thereof.

I’m definitely new to it, so if you could point me in the right direction I would appreciate it. What exactly is controversial about it? Hasn’t the equation been proven? And wouldn’t other methods of reasoning simplify down to Bayesian methods?

What I’m saying is that if you believe that God’s existence is extremely improbable given your background knowledge, then it does seem more likely that you will say that it needs “extraordinary evidence.” But the point I made in this post is that there are all kinds of claims that can be made which may seem extraordinary, but do not require any kind of “extraordinary” evidence. Cf. the example of simply seeing something. It is not “extraordinary evidence” to perceive something; yet it would certainly justify belief that an object one perceives exists, whether or not one thought that such things existed. So I think you’re coming at me from the wrong angle here. My points in this post are a direct attack on the idea of “extraordinary evidence”; that is, I’m not at all convinced there is such a thing.

Assuming Bayesian methods apply (for the sake of argument)…
If you are talking about, say, the claim that you are an extraterrestrial life form, that would be an ‘extraordinary claim’ because it has a very low prior probability. While the evidence may not need to be shocking or far-fetched, which is one way the phrase ‘extraordinary evidence’ could be understood, we would still need a high consequent probability (which is what I would define as ‘extraordinary evidence’).

Now what you’ve proposed is that the way to determine an “extraordinary claim” is to look at background knowledge. But if that’s how you want to define it, then any claim which seems out of the ordinary to an individual can in some way be extraordinary. And that’s why I say it implies radical subjectivism.

I can see where you would come to that conclusion. However, I think it is reconciled when we try to justify the conclusions to others.

But the subjectivity of priors is actually not a problem for [Bayes’ Theorem]. The fact of their subjectivity does not prevent us from producing conclusions that are as objective as can possibly be, given the limits of our knowledge and resources. Because subjective does not mean arbitrary. You must have reasons for your subjective estimates, so you must confront what those reasons are. And in defending your conclusion to anyone, you must be able to present those reasons to them, and those reasons had better be widely convincing. If they aren’t, you need to ask why they ever convinced you… You may be hesitant to assign probabilities because it seems arbitrary and subjective. But the point is to translate your actual beliefs into a more convenient language. You already have those beliefs. So translating them into numbers does not make them any more arbitrary and subjective than they already are.
-Richard Carrier

It seems to me that at face value, ‘extraordinary claims require extraordinary evidence’ is an English form of Bayes’ Theorem.

Basically, what I’m saying is that you’re assuming Bayesian epistemology is the only (or perhaps the best) game in town. I’m not convinced. Further, Carrier’s quotes are particularly unconvincing. For example, you quoted him as saying, “You may be hesitant to assign probabilities because it seems arbitrary and subjective. But the point is to translate your actual beliefs into a more convenient language. You already have those beliefs. So translating them into numbers does not make them any more arbitrary and subjective than they already are.”

Of course, this is exactly one of the major problems with Bayesian epistemology, and Carrier (in this passage at least) provides no justification for his contention. It does indeed seem very arbitrary to just assign numbers to your beliefs.

Now, I do think Bayesian epistemology has its merits. What I’m not so convinced by is the utter reliance you’ve had on it in order to try to carry your point.

One of the points he makes is that assigning subjective numbers is no different than a common phrase like “I think it’s likely.” Does “likely” mean 51%? Does it mean 60%? 90%? He provides phrases and what he thinks the percentage will correspond, but he says that ultimately, you come at a more objective number by argument and debate. (Keep in mind he’s arguing that Bayes’ Theorem should be used by scholars, so he says the numbers arrived at should reflect a general consensus.)

Is there a difference in saying “I think it’s probable” or “I think there is roughly an 80% chance of it being true”?

Yes, there is a difference, and that difference is that when I say something is “probable” I don’t have in mind a number. Plus, when you say “roughly an 80% chance” that’s where on of the difficulties lie as well. If your numbers are off by a certain margin (and note that these numbers are simply assigned to phrases like “likely” and “probable”) then the computation of something’s being true could drastically change.

But then, as I noted, this is only one problem with using Bayes’ theorem as you are. Now I do think Bayes theorem is very useful, and I have used it in the past and I will do so in the future during arguments. What I’m saying is the way you are using it–to try to show, for example, that it is the arbiter of all beliefs and that it justifies “extraordinary claims need extraordinary evidence”–falls victim to many (all?) of the problems cited with Bayes’ theorem.

While you may not have a specific number in mind, the words people use do have a general meaning. Saying “I think it might have happened” has a lower percentage than “I’m almost certain.” Whenever you say these things you aren’t thinking 60% or 99.999%, but it is clear that each phrase entails a different percentage. Yes, if the numbers are off by a certain amount it could change the result. But being off by .0001% is almost insignificant, so that scholars would focus on things that would make a difference.

But you just listed Carrier’s statements as support of your position. It seems pretty strange to read your support of the “roughly an 80% chance” phrase in light of what you just wrote here. Maybe I think that “probable” is 70%. Well 10% is a really huge difference. And to think that we’re going to get some kind of scholarly consensus about the likelihood of certain things is absurd. To take a non-religious example, I’m a fairly avid reader of WW2 history. There is great debate over whether the Battle of Midway was won by the U.S. due to sheer blind luck or skillful tactics (combined with poor Japanese intelligence data). There is a kind of naivete in thinking that “scholars” could come to a consensus opinion on assigning probabilities to epistemological reasoning about God, let alone less controversial historical claims.

Now again, I’ll note you have not even attempted to address the fact that I pointed to a number of objections to the use of Bayesian reasoning you’re pressing. I’ve given any number of reasons why I think your use of Bayes’ theorem in the context of this post fails, and you’ve yet to answer them, other than by saying things which seem to betray a lack of study in the area (i.e. equivocating between the mathematical soundness of Bayes’ theorem and its use in epistemology). Perhaps it may be best to delve more into a study of the issues involved than trying to shore up defenses around what I’ve already shown to be faulty reasoning.

But even if you think “probably” means 70% instead of 80%, you’re still thinking of a number. Yes, 10% can be quite a big difference, but you still have a probability in mind. If you have two people thinking something is “probable” but don’t agree on the conclusion, then Bayes’ Theorem will show where the conflict is, meaning they are able to focus on the disagreement instead of getting distracted. Bayes’ Theorem allows for scholars to come to more objective conclusions. How would these points you make against Bayes’ Theorem not also apply to any other form of reasoning? All Bayes’ Theorem does is just make it obvious.

Why is it naive to think scholars could come to an agreement? They come to agreements on many things, and the fact that there are some things they don’t doesn’t take away from that.

What points have you missed that I’ve failed to address? I thought we were talking about all of them, so it was not my intention to pass over any of them.

Specifically, you asked me how Bayesian reasoning is controversial, and I directed you to a number of objections to the type of reasoning you’re using. Secondly, just the fact that I agree we can assign numbers to things does not allow the “extraordinary claims need extraordinary evidence” phrase to follow. Thirdly, about the agreement of scholars–what I’m saying is that because there is extreme disagreement about things like even the Battle of Midway’s fortuitousness, it is essentially impossible that anyone on either side of the debate will agree that one is giving a fair probability to the existence of God.

Basically, the argument I have maintained is this: your use of Bayesian reasoning is without justification. When I asked you to justify the claim, you equivocated between the mathematical soundness of the theory and its epistemological usefulness. Just demonstrating a mathematical theorem is sound does not mean its application to epistemological concepts is uncontroversial (cf the link I provided). There are an extraordinary number of objections to the type of reasoning you’re using, and I have yet to see an argument in its favor other than that we may assign percents to our beliefs (I don’t operate that way, but I could see translating certain beliefs into degrees of certainty). Of course, this alone allowed me to object that given the Bayesian process, results can vary significantly between two people. You granted this but press that “Bayes’ Theorem will show where the conflict is, meaning they are able to focus on the disagreement instead of getting distracted. Bayes’ Theorem allows for scholars to come to more objective conclusions.”

Well of course! But if there is a disagreement over whether someone thinks something is 70 or 80% likely, that isn’t going to be solved by Bayesian reasoning. Such reasoning would be viciously circular.

So I think I have yet to see an argument on your side carry regarding your usage of Bayesian reasoning.

Finally, applying back to the original reason you commented, I still see no reason to think that Bayes’ theorem allows the “extraordinary claims” statement to have any merit.

Specifically, you asked me how Bayesian reasoning is controversial, and I directed you to a number of objections to the type of reasoning you’re using.

The main objection that I see you pointing out is the subjective priors, which is something we are still discussing, so I don’t see how this is a point I didn’t address. Did I miss another point?

Secondly, just the fact that I agree we can assign numbers to things does not allow the “extraordinary claims need extraordinary evidence” phrase to follow.

Sure it does. If we assign what we think is the probability of an event happening, then there is an amount of evidence that would change the conclusion from what we would expect. The only possible objection you could make to this without calling into question the mathematical proof of the Theorem is that the numbers would be subjective, but that isn’t an actual objection because 1) it would be subjective whether it was in Bayes’ Theorem form or any other form of reasoning, 2) saying something is extraordinary is subjective anyways.

Thirdly, about the agreement of scholars–what I’m saying is that because there is extreme disagreement about things like even the Battle of Midway’s fortuitousness, it is essentially impossible that anyone on either side of the debate will agree that one is giving a fair probability to the existence of God.

I didn’t mean to make it sound like Bayes’ Theorem is going to solve all of history’s problems, but my point is that it brings out the disagreements so they can be focused on. If there is a disagreement, it won’t be solved any more by a random form of reasoning (even the ones we currently use) than it will by Bayes’ Theorem, but the Theorem makes the conflicts more obvious.

Basically, the argument I have maintained is this: your use of Bayesian reasoning is without justification.

[Bayes’s Theorem] or not, either you could back up all these adverbs and assertions when you used them before, or you couldn’t. If you couldn’t, then you were being as subjective as you could ever accuse BT of being. But if you could back them up, then you can in BT just as well. So BT is no more subjective than any other form of historical argument. And when used properly, it is as objective as any historical method could ever be. Historians all have some idea of what was typical or atypical in the period and culture they study, and they can often make a case for either from the available evidence. If they can’t, then they must admit they don’t know what was typical, in which case they can’t say one theory is initially more likely than another. The prior probabilities are then equal. Likewise, if historians can’t defend a particular estimate of consequent probability, then they need to lower or raise that consequent until they can defend it. And if they can’t defend any value, then they cannot claim to know whether the evidence supports or weakens their hypothesis (or any other hypothesis for that matter). This follows whether historians use BT or not… So you might as well use BT. Because you can’t get any better result with any other method.

Well of course! But if there is a disagreement over whether someone thinks something is 70 or 80% likely, that isn’t going to be solved by Bayesian reasoning. Such reasoning would be viciously circular.

It wouldn’t be solved by any other type of reasoning, either.

Finally, applying back to the original reason you commented, I still see no reason to think that Bayes’ theorem allows the “extraordinary claims” statement to have any merit.

Because by definition, an extraordinary claim would be something with a low prior probability, and extraordinary evidence would be something with a high consequent probability.